Inductively-actuated loud-speaker



Jan. 14, 1930. J. DEPEW 1,743,265

INDUCTIVELY ACTUATED LOUD SPEAKEE 'Filed Feb. 12, 1926' zzgww ATTORNEY Patented Jan. 14, 1930 jun 'rs OFF! JOHN DEPEW, OF NEW YQRK, N. Y., ASSIGNOR T IGNATZ LAUTER,.OF NEW YORK, N.

INIbUCTIVELY-ACTUATED LOUD-SPEAKER Application filed February 12, 1926. .Serial No. 87,975.

My invention relates toloud speakers'of the general type suitable for use with radio. broadcasting receivers, electrically operated sound amplifiers, receivers of various types used in wire and Wireless telephony, and in fact in practically all relations in'which loud sounds are to be produced initially, or ordinary sounds are to be amplified, by means of small initial variations in the electromotive force or amperage of electric. currents.

In my improved loud speaker I take ad-. vantage of the attraction and repulsion de- Y Figures 1 and2.

veloped between twowindings when energized by alternating or oscillating currents. I make these windings of the pancake type,

' one of the windings being movable wholly or in part relativelyto the other and preferably carrying a thin imperforate member. of

sheet material adapted to serve as an acoustision of the windings when said windings aref cal diaphragm and to produce sounds when actuated.

As an alternative I"may make the two windings stationary andplace a diaphragm, made very lightandof insulating material, between them. This diaphra m would be made to vibrate by the attracti n and repulenergized, and thus to produce sounds.

'In addition I take advantage of the fact that the efficiency of the winding for the pur .poses here contemplated may be greatly improved by so energizing the windings that the action of one is retarded slightly in rela-- tion to the other, the retardation being caused by an impedance properly arranged in the circuit or circuits in which the windings are included and whereby they are energized.

Other objects and aims of theinvention, more or less specific than those referred to aboveywill be in part obvious 'and' in part pointed out in the course of the following description of the elements, combinations, arrangements of parts and applications of principles, constituting the invention, and the scope of protection contemplated will be indicated in the appended claims.

In the accompanying drawings which are to be taken as a part of this specification, and in which I have shown merely a pre- A supporting base appears at 4, and is provided with a slideway 5, as-shown more particularly in Figure 2. A spider ring 6, made of insulating material, is fitted loosely into the slideway, resting upon the bottom thereof as indicated in Figure 2, and is thus free to slide back and forth, with a. vibratory motion, within limits permitted by the width of the slideway. The spider ring is provided with an annular groove 7. For illustrative purposes this ring is here shown as rather massive, but it can be made as thin and light as conditions may require.

A pancake windi'ngis shown at 8. This is made of an insulated wire wound spirally and preferably having as a whole the proxie mate form of a cone. A. thin and light sheet of insulating material. 9 is secured to the winding by means-of shellac orother appropriate adhesive and is thus carried bodily by the winding and movable therewith. The purpose of the sheet 9 is t\vo-fold, first, 'to give strength and rigidity to the winding, and second, to render the winding imperforate, both so that .it may properly and ef- .ficiently act as an acoustical diaphragm, and

here it is noted that if desired the sheet 9 may be omitted and a coating of shellac or the like applied to the winding be relied upon to give the required strength and rigidity.

Ineither instance the winding 8 is secured to the ring 6 for support.

A second pancake winding as 11, is rigidly secured to the base by means of the attachin'g part 10 of the base. This last mentioned pancake winding-is also made of insulated i 18, a B battery at 19, an A battery at 20, a-

. two pancake wire wound in the same form as the winding 8 so as to stand parallel therewith the various convolutions being spaced apart, and secured or braced by means of sectors 13 of shellac or other appropriate binding and insulating material applied practically as a cement and then allowed to dry and harden.

By this means the winding 11 is made to permit the easy passage of air and sound waves therethrough from the diaphragm winding 8.

A conducting wire 12 may be used to connect together the two pancake windings so that they are in series or otherwise with each other relatively to the circuit whereby they are energized.

The diaphragm winding 8 is provided with a binding post 15, and the stationary winding 11 is similarly provided with a binding post 16.

The direction in which the wires of the respective windings are wound is preferably such that, reckoning from the binding posts 15 and 16, the direction is the same, or in other words that from the binding posts, the wires run. parallel with each other. How ever, if desired, this arrangement can be reversed, so that from a given point the direction'of one of the windings relatively to its binding post is clockwise and the direction of the other is counter-clockwise.

An audion tube appears at 17, an aerial at filament at 21, and at 22 is a circuit including the A battery and the filament 21, and thus designated as the filament circuit.

The aerial 18 is connected by an aerial wire 23 with the audion grid 24.

From the B battery 19 a wire 25 leads to an impedance coil 26. While this impedance winding is here shown conventionally and thus without an iron core, it may if desired be provided with an iron core. However, any other form of impedance may be substituted for the impedance coil 26. Connected with the impedance coil 26 is a wire 27, to which is joined a wire 28, leading to a binding post 15, and a wire 29, leading to the plate 30 of the audion tube 17.

Connected with B battery 19 is a wire 31.

Connected with this wire is a wire 32, leading to the binding post 16, and another wire 33. Connected with the wire 33 is a wire 34, leading to the heating circuit 22. and a ground wire 35, communicating with the earth at 36 through the medium of a grounding switch 37 here shown as open.

A purpose of the impedance coil 26 is to retard the action of the diaphragm winding 8 relatively to that of the stationary winding 11, and thus by slightly displacing the current phases of the two pancake windings to increase the attraction and repulsion of the windings relatively to each other.

By virtue of the slight phase'displacement brought about by the action of'the impedance coil 26 as just described, and the consequent lagging in the action of the diaphragm winding 8, differences of potential, necessarily developed between the diaphragm winding 8 and the stationary winding 11, are rendered dependent upon, and controllable by, the action of the audion 17.

The effect of the attraction and repulsion between the windings is to cause the winding 8, to move as a unit bodily back and forth relatively to the winding 11, and thus to act as a diaphragm and throw off sounds. These sounds are made up of sound waves having the characteristics of the sound'waves which, at a distant station, as for instance a broadcasting station, control the production of electro-inagnetic waves which travel through space and energize the audion 17 by means of the aerial 18, aerial wire 23 and audion grid 24.

The circuits. except for the action of the impedance coil 26 as above described, are well known and need no further description.

In the form of my device shown in Figure 3 the supporting base appears at 38, and

carries a stationary ring 39, provided with a Both of these windings are constructed with binder sectors 44 for the same purpose as described for the stationary winding 11.

The two pancake windings 43 and 45 are spaced slightly apart and loosely located within this space is a diaphragm 46, made very thin and light, and of insulating material.

The operation of the form shown in Figure 3 differs from that of the other form in that the two pancake windings 43 and 45 are each always stationary, and the diaphragm 46 is free to vibrate between them, being alternately attracted and repelled by each of them in succession.

The circuits employed would be the same as already described.

Owing to the retardation or lagcaused by the impedance coil 26, substantially as above described, the pancake winding 43 is energized an infinitesimal period of time before or after the pancake winding 45, each time there is a variation in the electromotive force of the battery current. This retardation or lag causes the pancake windings to act at slightly different moments upon the diaphragm 46, the result being that the movements of this diaphragm, first in one direction and then oint out, in addition, that in my device: 1 the diaphragm though made of considerable area, is easily energized throughout 'prac-, tically its eritire area; and that this fact makes 5 for greatlyimprov'ed'elficincy.

While I show 'mydnvention as used in com nection with an aerial and thus asunder con- -trol of electromagnetic waves,it will be linderstoodi that Izmay substitute any known 0 equivalent for the aeriaLfand thus may con: trol my device by means of a telephone line or byany' other agency capab'le of energizing arraudion or equivalent instrument in the convehtional manner". Thus the. particular "aircuit shown and described isnotessential. WVhile Iliave shown and described a particular means forlielding the platesand the jdiaphragmin their respective operative po sitions nevertheless any other appropriate means may obviously be employed to this end:

It will also be'lmdersfood that Iclaim for my loud speaker all of the uses to whicha loud speaker can be applied, and that as many changes could; be made in this construction without departing from the scope of the inyent ion as deiinedin-the-following'6laims, it is intended'that all matter contained in the above description 'or shown in the accompanying drawings shall be interpreted as illustrative only and not in a limiting sense;

Having thus described my invention, what I claim as new and'desire to secure by Letters Patent is 1 electromotive force for the purpose of using it to attract and repel said diaphragm.

- 4.. A'device of the character described comprising a pair of pancake windings spaced apart'and disposed in parallel relation to each other, means for energizing-said pancake windings by charging them in opposite sign a and to varying degrees of electromotive force, 7

means for retarding the action of one of said 7 windings relatiyely to'the other, and a dia- 7 -phragm located between said pancake wind- ;mgs and movable relatively thereto, said diaphragmbeing made of insulating material.

5 A device of the character described comrisihg a pair of pancake windings arranged in (substantially. parallel relation close together, means for variably energizing said windings, and a diaphragm ofinsulating material disposed'adjacent both of said windings, and movablerelatively thereto 85 In testimony whereof I aflix m signature. JOHN EPEWQ .1, A device of the class described compris B ing a pair of pancake windings spaced apart and disposed in parallel relation to "each other,rheans for charging said pancake windihgs in opposite sign andto varying degrees of electrornotive force, means for retarding 40' the actioh ofoneof said windin' s relative to p the other, and a diaphragm ma e of irisulat-- ing material and disposed adjacent both of said pancake windings;-and movable by the attraction andrepulsion'thereofl 2. A device of the class described, comprisinga diaphragm ofi insulating-material and a f pair of pancake windings,tsaid diaphragm and said pancake windin s being nestedtogether'and each haying t e proximate form V 0 'ofa cone, said diaphragm being suitably positioned to be acted upon by both ofsaid ancakewindings, means for subjecting b0 of said pancake windings to variations in electromotive force, and meansforretarding the action, upon said diaphragm,.of one of said pancake windings relatively to the other one.

3. A device of the class described comprising a pancake. winding having the general proximate form of a cone, a dia hragm loose relatively to said pancake winding and having also the proximate form' of a cone, said diaphragm being made of insulating material'and movable bodily in relation to said pancake winding, and means for subjecting said pancake winding to varying degrees-of 

